Abstract:

There is provided a paper width detection apparatus including a plurality
of lever members lined in parallel in a paper width direction of a
recording paper roll, each lever member being rotatably arranged on a
same center axis, a detecting unit for detecting a rotation state of the
lever member, and a determination unit for determining a paper width of
the recording paper roll based on a detection result. One lever member of
the plurality of lever members rotates in a first rotating direction
about the center axis by contacting an outer peripheral part of a holding
unit for holding both ends of the recording paper roll, and another lever
member positioned on an inner side in the paper width direction facing
the recording paper roll than the lever member contacting the holding
unit rotates in conjunction with the lever member contacting the outer
peripheral part of the holding unit.

Claims:

1. A paper width detection apparatus, comprising:a plurality of lever
members lined in parallel in a paper width direction of a recording paper
roll attached to a recording paper roll loading unit, each lever member
being rotatably arranged on a same center axis;a detecting unit for
detecting a rotation state of the lever member; anda determination unit
for determining a paper width of the recording paper roll based on a
detection result detected by the detecting unit;wherein one lever member
of the plurality of lever members rotates in a first rotating direction
about the center axis by contacting an outer peripheral part of a holding
unit for holding both ends of the recording paper roll, andanother lever
member positioned on an inner side in the paper width direction facing
the recording paper roll than the lever member contacting the holding
unit rotates in conjunction with the lever member contacting the outer
peripheral part of the holding unit.

2. The paper width detection apparatus according to claim 1, whereina
second lever member positioned on an outer side in the paper width
direction of the lever members adjacent in the paper width direction
includes a projection projecting towards a first lever member positioned
on the inner side in the paper width direction, andwhen the second lever
member rotates in the first rotating direction, the projection of the
second lever member contacts the first lever member, and the first lever
member rotates with the second lever member.

3. The paper width detection apparatus according to claim 1, whereinthe
lever member includes,a main body unit having a contacting part, which
contacts the outer peripheral part of the holding unit, at one end and a
through-hole to be inserted with the center axis on another end, anda
back end which is coupled to the other end of the main body unit and
which rotation state is detected by the detecting unit, andthe
determination unit determines the paper width of the recording paper roll
based on number of detections the back end is detected by the detecting
unit by the rotation of the lever member.

4. The paper width detection apparatus according to claim 3, whereinone
lever member of the plurality of lever members contacts an outer
peripheral surface of a flange unit and rotates in the first rotating
direction when the recording paper roll loading unit is inserted to a
housing from an initial state in which the lever member is drooped such
that the contacting part is positioned on an upper side than a center of
rotation of the recording paper roll loading unit; andthe one or more
rotated lever members return to the initial state when the recording
paper roll loading unit is pulled out from the housing.

5. The paper width detection apparatus according to claim 4, further
comprising an elastic member for biasing the lever member in a second
direction opposite to the first rotating direction.

6. An image forming apparatus comprising:a recording paper roll loading
unit, detachably arranged with respect to a housing, for accommodating a
recording paper roll formed by rolling up a recording paper to a
roll-form;a paper width detection mechanism for detecting a paper width
of the recording paper roll accommodated in the recording paper roll
loading unit;a paper conveying unit for conveying the recording paper;a
printing unit for performing a printing process on the recording paper
conveyed by the paper conveying unit; anda cutting unit for cutting a
printed region printed by the printing unit of a recording medium,wherein
the paper width detection mechanism includes,a plurality of lever members
lined in parallel in the paper width direction of the recording paper
roll attached to the recording paper roll loading unit, each lever member
being rotatably arranged on a same center axis,a detecting unit for
detecting a rotation state of the lever member, anda determination unit
for determining the paper width of the recording paper roll based on a
detection result detected by the detecting unit,one lever member of the
plurality of lever members rotates in a first rotating direction about
the center axis by contacting an outer peripheral part of a holding unit
for holding both ends of the recording paper roll, andanother lever
member positioned on an inner side in the paper width direction facing
the recording paper roll than the lever member contacting the holding
unit rotates in conjunction with the lever member contacting the outer
peripheral part of the holding unit.

7. The image forming apparatus according to claim 6, whereinthe holding
unit includes,a fixed unit inserted to a center part of the recording
paper roll to act as a rotation shaft of the recording paper roll, anda
movable unit on a circular plate, coupled to the fixed unit, for
regulating an end face position of the recording paper roll, anda guide
unit projected or recessed in a radial direction is formed along a
peripheral direction at an outer peripheral part, which is an outer edge
of the movable unit.

[0004]In an image forming apparatus such as a printer and a copying
machine, a cut paper, which is cut to a predetermined size in advance,
and a roll paper, which is rolled up to a rolled form, are used as a
recording medium for recording images. Recently, with the spread of
digital cameras, the roll paper, which is advantageous in terms of cost
in high quality printing, is widely used. The roll paper is formed by
rolling up a long recording paper on a paper core that acts as a rolling
core, and is pulled out by a necessary amount for every printing and
conveyed to a printing unit, and then cut to a predetermined size and
discharged from a discharging unit after printing is finished.

[0005]With the spread of the roll paper, type and size such as width
dimension of the roll paper have diversified. On the other hand, an image
forming apparatus capable of loading roll papers of different size tends
to increase. In such image forming apparatus, a setting and a driving
method suited to the size to be used are selected, where a majority of
the image forming apparatus includes a size detection means for detecting
the size of the roll paper. The image forming apparatus is able to
automatically perform setting suited to the paper size to be used, based
on the detection result of the size detection means.

[0006]For instance, Japanese Patent Application Laid-Open No. 2005-320101
discloses a size detection means configured to include a mirror piece
that oscillates by a cam arranged at an end face of a flange member for
holding the roll paper, a light source for irradiating light to the
mirror piece, and a sensor for detecting a reflected light of the mirror
piece. Such size detection means calculates the time between the time
point the reflected light is detected in moving towards right and the
time point the reflected light is detected in moving towards left in one
period in which the mirror piece oscillates to the left and the right,
and calculates a paper width from the relevant time.

[0007]Furthermore, Japanese Patent Publication No. 2848062 discloses a
paper size detection device including a size detection mechanism at a
predetermined position of a downstream portion of a conveyance roller
device. Such size detection mechanism is arranged at a joining portion of
a paper conveyance path, and detects the paper size by being configured
with a plurality of sensors arranged with respect to the paper conveyance
path.

SUMMARY OF THE INVENTION

[0008]However, the size detection means described in Japanese Patent
Application Laid-Open No. 2005-320101 has an issue in that the mirror
piece may not be oscillated unless the flange member is rotated, and thus
lacks in immediate decision property of the paper size. Furthermore, the
addition of the mechanism such as the cam and the mirror piece is desired
with respect to the flange member, and high precision is desired for the
configuration thereof. When detecting the recording paper being conveyed
in the paper conveyance path as described in Japanese Patent Publication
No. 2848062, the paper size is not able to be detected until the paper
passes the position where the sensor is arranged, and thus lacks in
immediate decision property. Furthermore, periodic maintenance is
necessary since paper powder, and the like in the paper conveyance path
tends to accumulate in a light emitting unit and a light receiving unit.

[0009]The present invention has been made in view of the above issue, and
it is desirable to provide a novel and improved paper width detection
apparatus and an image forming apparatus capable of immediately judging
the paper size and reliably detecting the paper size with a simple
configuration.

[0010]According to an embodiment of the present invention, there is
provided a paper width detection apparatus including a plurality of lever
members lined in parallel in a paper width direction of a recording paper
roll attached to a recording paper roll loading unit, each lever member
being rotatably arranged on a same center axis, a detecting unit for
detecting a rotation state of the lever member, and a determination unit
for determining a paper width of the recording paper roll based on a
detection result detected by the detecting unit. One lever member of the
plurality of lever members rotates in a first rotating direction about
the center axis by contacting an outer peripheral part of a holding unit
for holding both ends of the recording paper roll, and another lever
member positioned on an inner side in the paper width direction facing
the recording paper roll than the lever member contacting the holding
unit rotates in conjunction with the lever member contacting the outer
peripheral part of the holding unit.

[0011]According to the present invention, one lever member of a plurality
of lever members contacts an outer peripheral part of a holding unit and
rotates, and another lever member, which is positioned on an inner side
in a paper width direction than the contacting lever member, rotates in
conjunction therewith. The paper width direction herein described is the
width in a direction orthogonal to the rolling direction of the recording
paper roll. The inner side in the paper width direction having an
arbitrary lever member as a reference is the recording paper roll side,
and the outer side in the paper width direction is the side opposite to
the side arranged with the recording paper roll. A detecting unit detects
the rotated lever member, and a determination unit determines the paper
width of the recording paper roll based on the detection result of the
detecting unit. Thus, the paper width of the recording paper roll can be
detected with a simple configuration. Furthermore, the lever member can
be prevented from contacting the recording paper roll by rotating the
lever member positioned on the inner side in the paper width direction
than the lever member contacting the outer peripheral part of the holding
unit in conjunction.

[0012]Here, a second lever member positioned on an outer side in the paper
width direction of the lever members adjacent in the paper width
direction includes a projection projecting towards a first lever member
positioned on the inner side in the paper width direction. When the
second lever member rotates in the first rotating direction, the
projection of the second lever member contacts the first lever member,
and the first lever member rotates with the second lever member.

[0013]Moreover, the lever member includes a main body unit having a
contacting part, which contacts the outer peripheral part of the holding
unit, at one end and a through-hole to be inserted with the center axis
on another end, and a back end which is coupled to the other end of the
main body unit and which rotation state is detected by the detecting
unit. At this time, the determination unit determines the paper width of
the recording paper roll based on number of detections the back end is
detected by the detecting unit by the rotation of the lever member.

[0014]Furthermore, one lever member of the plurality of lever members may
contact an outer peripheral surface of a flange unit and may rotate in
the first rotating direction when the recording paper roll loading unit
is inserted to a housing from an initial state in which the lever member
is drooped such that the contacting part is positioned on an upper side
than a center of rotation of the recording paper roll loading unit. The
one or more rotated lever members may return to the initial state when
the recording paper roll loading unit is pulled out from the housing.

[0015]Moreover, the paper width detection apparatus may further include an
elastic member for biasing the lever member in a second direction
opposite to the first rotating direction.

[0016]Moreover, according to another embodiment of the present invention,
there is provided an image forming apparatus including a recording paper
roll loading unit, detachably arranged with respect to a housing, for
accommodating a recording paper roll formed by rolling up a recording
paper to a roll-form, a paper width detection mechanism for detecting a
paper width of the recording paper roll accommodated in the recording
paper roll loading unit, a paper conveying unit for conveying the
recording paper, a printing unit for performing a printing process on the
recording paper conveyed by the paper conveying unit, and a cutting unit
for cutting a printed region printed by the printing unit of a recording
medium. The paper width detection mechanism includes, a plurality of
lever members lined in parallel in the paper width direction of the
recording paper roll attached to the recording paper roll loading unit,
each lever member being rotatably arranged on a same center axis, a
detecting unit for detecting a rotation state of the lever member, and a
determination unit for determining the paper width of the recording paper
roll based on a detection result detected by the detecting unit. One
lever member of the plurality of lever members rotates in a first
rotating direction about the center axis by contacting an outer
peripheral part of a holding unit for holding both ends of the recording
paper roll, and another lever member positioned on an inner side in the
paper width direction facing the recording paper roll than the lever
member contacting the holding unit rotates in conjunction with the lever
member contacting the outer peripheral part of the holding unit.

[0017]Here, the holding unit may include a fixed unit inserted to a center
part of the recording paper roll to act as a rotation shaft of the
recording paper roll, and a movable unit on a circular plate, coupled to
the fixed unit, for regulating an end face position of the recording
paper roll. At this time, a guide unit projected or recessed in a radial
direction is formed along a peripheral direction at an outer peripheral
part, which is an outer edge of the movable unit.

[0018]According to the embodiments of the present invention described
above, a paper width detection apparatus and an image forming apparatus
capable of immediately judging the paper size and reliably detecting the
paper size with a simple configuration can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a cross-sectional view showing a schematic configuration
of an image forming apparatus according to an embodiment of the present
invention;

[0020]FIG. 2 is a perspective view showing a recording paper roll and a
holding unit for holding the same according to the embodiment;

[0021]FIG. 3 is a partial perspective view showing a schematic
configuration of a paper width detection mechanism according to the
embodiment;

[0022]FIG. 4 is a partial perspective view showing the configuration of
the paper width detection mechanism according to the embodiment in
detail;

[0023]FIG. 5 is an exploded perspective view showing a configuration of a
lever member of the paper width detection mechanism according to the
embodiment;

[0024]FIG. 6 is an exploded perspective view showing a configuration of a
lever member of the paper width detection mechanism according to the
embodiment;

[0025]FIG. 7 is an exploded perspective view showing a configuration of a
lever member of the paper width detection mechanism according to the
embodiment;

[0026]FIG. 8 is a plan view showing the lever member according to the
embodiment;

[0027]FIG. 9 is a bottom view showing the lever member according to the
embodiment;

[0028]FIG. 10 is a perspective view showing a configuration of a holder
according to the embodiment;

[0029]FIG. 11 is a partial perspective view showing an outline of a usage
state of the paper width detection mechanism according to the embodiment;

[0030]FIG. 12 is an explanatory view showing a state in which a recording
paper roll loading unit is attached to a housing of the image forming
apparatus;

[0031]FIG. 13 is an explanatory view showing the operation of the lever
member in the attachment of the recording paper roll loading unit to the
housing;

[0032]FIG. 14 is an explanatory view showing a state in which a first
lever member is contacting a flange unit;

[0033]FIG. 15 is an explanatory view showing a state in which a second
lever member is contacting a flange unit; and

[0034]FIG. 16 is an explanatory view showing a state in which a third
lever member is contacting a flange unit.

DETAILED DESCRIPTION OF THE EMBODIMENT

[0035]Hereinafter, preferred embodiments of the present invention will be
described in detail with reference to the appended drawings. Note that,
in this specification and the appended drawings, structural elements that
have substantially the same function and structure are denoted with the
same reference numerals, and repeated explanation of these structural
elements is omitted.

[0036]The present embodiment will be described in the following order.

[0037]First, a schematic configuration of an image forming apparatus 100
equipped with a paper width mechanism 120 according to the embodiment of
the present invention will be described based on FIGS. 1 and 2. FIG. 1 is
a cross-sectional view showing a schematic configuration of the image
forming apparatus 100 according to the present embodiment. FIG. 2 is a
perspective view showing a recording paper roll 10 and a holder 130 for
holding the same according to the present embodiment.

[0038]A sublimation thermal printer device, as shown in FIG. 1, may be
used for the image forming apparatus 100 equipped with the paper width
detection mechanism 120 according to the present embodiment. The
sublimation thermal printer device is an image forming apparatus that
uses an exothermic energy of when current is carried to a heat generating
element in a thermal head to sublimate a sublimation dye applied on an
ink ribbon, and transfer and print on a recording paper. As shown in FIG.
1, such image forming apparatus 100 includes a recording paper roll
loading unit 110, the paper width detection mechanism 120, a paper
conveying unit 140, an ink supplying unit 150, a printing unit 160, a
fold-back unit 170, and a cutter unit 180.

[0039]The recording paper roll loading unit 110 is a mechanism for
accommodating a recording paper roll 10, and is detachably arranged with
respect to a housing 102 of the image forming apparatus 100. The
recording paper roll loading unit 110 includes an accommodating portion
112 for accommodating the recording paper roll 10. The recording paper
roll 10 is formed by rolling up a recording paper on a tubular shaft part
to a rolled form. As shown in FIG. 3, the holder 130 is attached to both
ends of the recording paper roll 10 to rotatably attach the recording
paper roll 10 to the recording paper roll loading unit 110. The
accommodating portion 112 is formed to a substantially semicircular
recess along the shape of an outer circumferential surface of the
recording paper roll 10, and covers part of the outer circumferential
surface of the accommodated recording paper roll 10. The recording paper
roll loading unit 110 rotatably supports a supporting portion 132 of the
holder 130 attached to the recording paper roll. A paper feeding roller
114 for feeding the recording paper forming the recording paper roll 10
to a conveyance path is arranged so as to contact an outermost
circumferential surface of the recording paper roll 10 accommodated in
the accommodating portion 112. The detailed configuration of the holder
130 will be hereinafter described.

[0041]The paper conveying unit 140 is a mechanism for conveying the
recording paper during the printing operation and the paper discharging
operation, and includes a pinch roller 142 and a capstan 144. The pinch
roller 142 and the capstan 144 are pressed and contacted to each other,
where the recording paper passing through the pressed and contacted
portion of the pinch roller 142 and the capstan 144 is conveyed by the
rotation of the pinch roller 142 and the capstan 144. For instance, the
recording paper conveyed by the paper feeding roller 114 from the
recording paper roll loading unit 110 is conveyed in the forward
direction to be guided to the printing unit 160 side, or the recording
paper of the conveyance path is conveyed in the reverse direction to be
wounded by the recording paper roll 10. The paper conveying unit 140 is
accurately forward/reverse rotation controlled by a control unit (not
shown).

[0042]The ink supplying unit 150 supplies ink used to form images on the
recording paper. The ink supplying unit 150 includes an ink ribbon 152, a
supply reel 154, and a winding reel 156. The ink ribbon 152 is color
coded for every ink color. The ink ribbon 152 is pulled out by the supply
reel 154, passed on a platen roller 162, and conveyed and wounded by the
winding reel 156.

[0043]The printing unit 160 is a mechanism for performing a printing
process on the recording paper, and includes the platen roller 162, and a
print head 164. The platen roller 162 is a roller member used in
printing. The print head 164 includes a heat generating element for
sublimating the sublimation dye of the ink ribbon 152, and is arranged at
a position facing the platen roller 162 with the conveyance path of the
recording paper in between. The print head 164 is configured to be
movable between a printing position where the recording paper and the ink
ribbon 152 are pressed with the platen roller 162, and a standby position
where the pressing on the recording paper of the ink ribbon 152 is
released by being separated from the platen roller 162.

[0044]The fold-back unit 170 is a paper conveyance path for changing the
conveying direction of the recording paper printed in the printing unit
160. As shown in FIG. 1, the fold-back unit 170 may be formed to a
substantially U-shaped path. According to such shape, the direction of
the recording paper that entered the fold-back unit 170 can be changed,
and the recording paper can be discharged. With the arrangement of the
fold-back unit 170, a limited space in the apparatus can be effectively
utilized, and an insert/exit direction of the recording paper roll
loading unit 110 and an opening direction of a discharge port 104 can be
faced in the same direction. The operability of the image forming
apparatus 100 thus can be enhanced.

[0045]The cutter unit 180 is a mechanism for cutting the recording paper,
and is arranged at the discharge port 104 of the image forming apparatus
100. The cutter unit 180 cuts the recording paper to a printed region and
a non-printed region in a length direction of the recording paper.

[0046]When information on the image to be printed on the recording paper
is input, the image forming apparatus 100 having the above configuration
feeds the recording paper from the recording paper roll loading unit 110
by means of the paper feeding roller 114, and conveys the recording paper
to the printing unit 160 by means of the paper conveying unit 140. When
the recording paper reaches the printing unit 160, the print head 164
approaches the platen roller 162, and the ink ribbon 152 pressure
contacts the recording paper. The print head 164 selectively
current-carry drives the heat generating element based on tone data to
sublimate the ink on the ink ribbon 152 and transfer to the recording
paper. The image thereby forms on the recording paper. Thereafter, the
recording paper is passed through the fold-back unit 170 and cut to a
predetermined size by the cutter unit 180, and the recording paper
including the printed region is discharged from the discharge port 104.

[0047]The schematic configuration of the image forming apparatus 100
according to the present embodiment has been described above. The image
forming apparatus 100 according to the present embodiment can replace to
the recording paper roll 10 of a different size to the recording paper
roll loading unit 110 and use the same. The image forming apparatus 100
according to the present embodiment includes the paper width detection
mechanism 120 to automatically detect the paper size (paper width in the
present embodiment) of the recording paper roll 10 accommodated in the
recording paper roll loading unit 110.

[0048]The configuration of the paper width detection mechanism 120
according to the present embodiment will be described in detail based on
FIGS. 3 to 11. FIG. 3 is a partial perspective view showing a schematic
configuration of the paper width detection mechanism 120 according to the
present embodiment. FIG. 4 is a partial perspective view showing the
configuration of the paper width detection mechanism 120 according to the
present embodiment in detail. FIGS. 5 to 7 are exploded perspective views
showing a configuration of a lever member of the paper width detection
mechanism 120 according to the present embodiment. FIG. 8 is a plan view
showing the lever member according to the present embodiment. FIG. 9 is a
bottom view showing the lever member according to the present embodiment.
FIG. 10 is a perspective view showing a configuration of the holder 130
according to the present embodiment. FIG. 11 is a partial perspective
view showing an outline of a usage state of the paper width detection
mechanism 120 according to the present embodiment.

[Configuration of Paper Width Detection Mechanism]

[0049]As shown in FIG. 3, the paper width detection mechanism 120
according to the present embodiment is arranged on the upper side of the
recording paper roll 10 accommodated in the recording paper roll loading
unit 110. The paper width detection mechanism 120 includes three lever
members 121, and can detect the paper size of three types. The distal end
portion of one of the lever members 121 is arranged to contact the outer
peripheral portion of the holder 130. The paper width detection mechanism
120 detects the paper width of the recording paper roll 10 accommodated
in the recording paper roll loading unit 110 based on the rotation
position of each lever member 121.

[0050]More specifically, the paper width detection mechanism 120 is
configured by the lever member 121, a detecting unit 122, a torsion
spring 123, and a supporting shaft 125, as shown in FIG. 4.

[0051]The lever member 121 is a plate-shaped member that rotates according
to the paper size of the recording paper roll 10 accommodated in the
recording paper roll loading unit 110. The lever member 121 according to
the present embodiment includes a first lever member 121a, a second lever
member 121b, and a third lever member 121c arranged in order from the
inner side towards the outer side in the paper width direction. Among
such lever members 121, one lever member 121 contacts the outer
peripheral part of the holder 130 attached to the recording paper roll
10, and rotates according to the paper width of the recording paper roll
10. Each lever member 121 rotates in conjunction with the lever member
121 positioned on the outer side in the paper width direction of the
recording paper roll 10 than itself. The detailed configuration of the
lever member 121 will be hereinafter described.

[0052]The detecting unit 122 detects the rotation of the lever member 121.
A detection element such as a photosensor and a magnetic sensor, or a
detection circuit substrate using a micro-switch and a lead switch may be
used for the detecting unit 122. The detecting unit 122 is arranged on a
detection circuit substrate arranged on an inner wall surface of the
supporting portion including a pair of side plates facing each other, and
a coupling plate for coupling the side plates. The detecting unit 122 is
arranged at one to one with the lever member 121. The detecting unit 122
is arranged at a position facing a back end (e.g., reference numerals
211b, 212b, 213b in FIG. 5) of the lever member 121 in a y-axis direction
when the lever member 121 is rotated. Alternatively, the detecting unit
122 may be arranged to face the back end of the lever member 121 in an
x-axis direction. When a contacting part of the lever member 121 contacts
the outer peripheral surface of the holder 130 and displaces in the
rotating direction, the back end of the lever member 121 is sandwiched by
the inner wall surface of the supporting portion, that is, the portion
surrounded by the side plates and the coupling plate. Thus, the detecting
unit 122 including the photosensor is light shielded, and the rotation
state of the lever member 121 is detected.

[0053]The torsion spring 123 is an elastic member for biasing the lever
member 121. The torsion spring 123 has the supporting shaft 125 inserted
to the inside of the wounded portion, and is supported by the supporting
shaft 125 with the lever member 121. With the reception of the biasing
force of the torsion spring 123, the lever member 121 is in a state in
which the contacting part is drooped when not contacting the outer
peripheral part of the holder 130, and is biased with respect to the
outer peripheral part when contacting the outer peripheral part of the
holder 130. The contacting part of the lever member 121 can freely rotate
against the biasing force of the torsion spring 123. If the lever member
121 is arranged such that the contacting part droops by its own weight
when not contacting the outer peripheral part of the holder 130, the
torsion spring 123 may be omitted.

[0054]The supporting shaft 125 is a shaft for supporting the lever member
121 and the torsion spring 123. The supporting shaft 125 has a locking
unit 125a that locks the supporting shaft 125 to the accommodating
portion 126 at one end, and a groove 125b at the other end. The
supporting shaft 125 is inserted to a through-hole passing in the paper
width direction of the recording paper roll 10 formed in the
accommodating portion 126, and is fixed to the accommodating portion 126
by engaging a fixing member 124 such as a retaining ring to the groove
125b. In this case, the lever member 121 and the torsion spring 123 are
accommodated inside the accommodating portion 126. The detecting unit 122
is arranged inside the accommodating portion 126 in correspondence to the
lever member 121.

[0055]The paper width detection mechanism 120 further includes a
determination unit (not shown) for determining the size of the recording
paper roll 10 accommodated in the recording paper roll loading unit 110
based on the detection result of the rotation state of the lever member
121 by the detecting unit 122. The determination unit is a micro-computer
etc. arranged on the detection circuit substrate including the detecting
unit 122. The determination unit determines the size of the recording
paper roll 10 according to the number of back ends 211b, 212b, and 213b
of the lever member 121 detected by the detecting unit 122 by the
rotation.

[Configuration of Lever Member]

[0056]The configuration of the lever member 121 of the paper width
detection mechanism 120 will now be more specifically described based on
FIGS. 5 to 9. With respect to the lever member 121, the x-axis positive
direction side is the plane, x-axis negative direction side is the bottom
surface, y-axis positive direction side is the front surface, y-axis
negative direction side is the rear surface, z-axis positive direction
side is the upper side surface, and z-axis negative direction side is the
lower side surface.

[0057]The lever member 121 is a light plate-shaped member integrally
formed from hard resin. Lighter weight and lower cost can be achieved by
using such lever member 121. The lever member 121 includes a main body
unit (211a, 212a, 213a), a back end (211b, 212b, 213b), and a
through-hole (211c, 212c, 213c).

[0058]The main body unit 211a, 212a, 213a is a plate-shaped member of
substantially rectangular shape in which the front surface and the rear
surface are rounded. The plane side of the main body unit 211a, 212a, and
213a is a flat surface, as shown in FIGS. 5 and 9. The bottom surface
side of the main body unit 211a, 212a, and 213a includes a flat portion
and a thin-thickness portion (211m, 212m, 213m) having a thickness in the
x-axis direction smaller than the flat portion, as shown in FIGS. 6 to 8.
The flat portion on the bottom surface side of the main body unit 211a,
212a, and 213a also has the thickness of the front surface portion (211h,
212h, 213h) become smaller towards the rounded distal end portion. A rib
(211g, 212g, 213g) extending in the y-axis direction is formed at the
flat portion on the bottom surface side of the main body unit 211a, 212a,
and 213a to reinforce the main body unit 211a, 212a, and 213a. The
thin-thickness portion 211m, 212m, 213m of the main body unit 211a, 212a,
and 213a contacts the outer peripheral surface of the holder 130 holding
the recording paper roll 10.

[0059]The through-hole 211c, 212c, 213c is formed at one side (y-axis
negative direction side) of the main body unit 211a, 212a, 213a coupled
with the back end 211b, 212b, 213b. The supporting shaft 125 is inserted
to the through-hole 211c, 212c, and 213c. Four protrusions (212d, 213d),
for example, are formed at the periphery of the through-hole 212c, 213c,
as shown in FIG. 5, at the through-hole 212c, 213c of the second lever
member 121b and the third lever member 121c. The protrusions 212d and
213d are provided to reduce the area of the portion having the
possibility of contacting the adjacent lever member 121.

[0060]The main body unit 211a, 212a, 213a of the lever member 121 includes
an engaging portion and an engaged portion to cooperatively rotate the
adjacent member 121. The engaging portion is a recess (211e, 212e) formed
on the lower side surface of the first lever member 121a and the second
lever member 121b. The engaged portion is a projection (212f, 213f)
arranged on the lower side surface of the second lever member 121b and
the third lever member 121c.

[0061]The recess 211e of the first lever member 121a engages the
projection 212f projecting in the x-axis positive direction side of the
second lever member 121b, and the recess 212e of the second lever member
121b engages the projection 213f projecting in the x-axis positive
direction side of the third lever member 121c. As shown in FIG. 5, the
recesses 211e, 212e opened in the z-axis negative direction have the
projections 212f, 213f contact the recesses 211e, 212e in the z-axis
positive direction when the lever member 121 positioned on the outer side
in the paper width direction than itself rotates along the outer
peripheral surface of the holder 130. The recesses 211e, 212e are pushed
up by the projections 212f, 213f. Thus, the lever member 121 can rotate
itself in conjunction with the lever member 121 positioned on the outer
side in the paper width direction (x-axis positive direction) than
itself.

[0062]In other words, the projections 212f, 213f arranged on the second
lever member 121b and the third lever member 121c transmit the power for
rotating the lever members 121a, 121b to the lever members 121a, 121b
adjacent on the inner side in the paper width direction. If the biasing
force of the torsion spring 123 is also transmitted only to the lever
member 121 positioned at the innermost part in the paper width direction
by coupling the adjacent lever member 121, the biasing force can be
transmitted to the adjacent lever member 121.

[0063]The back end 211b, 212b, 213b is coupled to the rear surface side of
the main body unit 211a, 212a, and 213a. The back end 211b, 212b, and
213b may be a fan-shaped plate member, as shown in FIGS. 8 and 9. The
back end 211b, 212b, 213b is arranged to be sandwiched by and face the
inner wall surface of the supporting portion for supporting the detecting
unit 122.

[0064]As shown in FIGS. 5 to 7, such lever member 121 has the
through-holes 211c, 212c, 213c inserted to the supporting shaft 125
inserted with the torsion spring 123 in the order of the first lever
member 121a, the second lever member 121b, and the third lever member
121c.

[Configuration of Holder]

[0065]The paper width detection mechanism 120 determines the paper width
by detecting the position of the outer peripheral part of the holder 130
holding the recording paper roll 10 accommodated in the recording paper
roll loading unit 110. As shown in FIG. 10, the holder 130 includes a
fixed bobbin 131 that is inserted to the rolling core of the recording
paper roll 10 and acts as a rotation shaft, and a movable bobbin 133 for
regulating the position of the end face of the recording paper roll 10.
The fixed bobbin 131 is arranged with a supporting shaft 132 that
projects out in a substantially perpendicular direction with respect to
the end face of the recording paper roll 10. A flange unit 134 having a
predetermined width in the x-axis direction is arranged at an outer edge
of the movable bobbin 133.

[0066]The lever member 121 contacts the flange unit 134. The position of
the flange unit 134 of when the recording paper roll 10 is accommodated
in the recording paper roll loading unit 110 displaces in the paper width
direction according to the paper width of the recording paper roll 10 to
which the holder 130 is attached. The lever member 121 that contacts the
flange unit 134 of the holder 130 and the lever member 121 positioned on
the inner side in the paper width direction (x-axis positive direction
side) than such lever member 121 rotates in a counterclockwise direction,
as shown in FIG. 11. The lever member 121 that does not contact the
flange unit 134, the lever member 121 being positioned on the outer side
in the paper width direction (x-axis negative direction side) than the
lever member 121 that contacts the flange unit 134, does not displace
from the initial state and droops.

[0067]A radially projecting guide unit 134a may be arranged along a
circumference in the x-axis negative direction side of the flange unit
134. The guide unit 134a may be arranged on the outer side in the paper
width direction of the flange unit 134. With the arrangement of such
guide unit 134a, even if the supporting shaft 132 of the holder 130
slightly rattles, the lever member 121 can be stably sled on the
peripheral surface of the flange unit 134 without being influenced by
such rattling. Thus, the possibility of mistaken detection by the paper
width detection mechanism 120 can be lowered as much as possible. The
diameter of the flange unit 134 is formed to be greater than the diameter
at the outermost part of the recording paper roll 10. Accordingly, the
lever member 121 and the surface of the recording paper roll 10 do not
contact when the lever member 121 at the position facing the recording
paper roll 10 rotates.

[Detecting Operation of Paper Width Detection Mechanism]

[0068]The paper width detecting operation of the recording paper roll by
the paper width detection mechanism 120 will now be described based on
FIGS. 12 to 16. FIG. 12 is an explanatory view showing a state in which
the recording paper roll loading unit 110 is attached to the housing 102
of the image forming apparatus 100. FIG. 13 is an explanatory view
showing the operation of the lever member 121 in the attachment of the
recording paper roll loading unit 110 to the housing 102. FIG. 14 is an
explanatory view showing a state in which the first lever member 121a is
contacting the flange unit 134. FIG. 15 is an explanatory view showing a
state in which the second lever member 121b is contacting the flange unit
134. FIG. 16 is an explanatory view showing a state in which the third
lever member 121c is contacting the flange unit 134.

[0069]The operation of when detecting the paper width of three types of
recording paper roll 10 with three lever members 121 will be described
herein. The sizes of the three types of recording paper roll 10 are eight
inch size (203 mm), A4 size (210 mm), and LT size (216 mm). The paper
width detection mechanism 120 according to the present embodiment can
accurately detect the paper width even if the sizes of the three types
differ by only a few millimeters. This is because the lever member 121
can be arranged in close proximity by reducing the thickness of the lever
member 121 (x-axis direction, i.e., paper width direction). In this case,
the ribs 211g, 212g, 213g are formed at the main body units 211a, 212a,
213a to reinforce the thinned lever member 121.

[0070]First, as shown in FIG. 12, the recording paper roll loading unit
110 according to the present embodiment accommodates the recording paper
roll 10 held by the holder 130, and is attached to the image forming
apparatus 100 from the opening 106 of the housing 102. In the initial
state of before the recording paper roll loading unit 110 is attached to
the housing 102, all of the three lever members 121 of the paper width
detection mechanism 120 are in a state drooped in the z-axis negative
direction. When the recording paper roll loading unit 110 is pushed into
the image forming apparatus 100, the lever member 121 of the paper width
detection mechanism 120 arranged inside the image forming apparatus 100
contacts the peripheral surface of the flange unit 134 of the holder 130
holding the recording paper roll 10, as shown in FIG. 13. In this case,
at least one of the three lever members 121 contacts the flange unit 134,
and rotates in the counterclockwise direction along the peripheral
surface thereof.

[0071]Among the recording paper roll 10 that can be accommodated in the
recording paper roll loading unit 110, the detection of the recording
paper roll 10 having the narrowest paper width (i.e., eight inch size
(203 mm)) is performed by the first lever member 121a. When the recording
paper roll loading unit 110 accommodating such recording paper roll 10 is
pushed into the housing 102, the first lever member 121a contacts the
flange unit 134. The first lever member 121a rotates along the peripheral
surface of the flange unit 134 with the pushing in of the recording paper
roll loading unit 110 into the housing 102.

[0072]When the recording paper roll loading unit 110 is attached to the
image forming apparatus 100, only the first lever member 121a of the
lever member 121 is rotatable, as shown in FIG. 14. In this case, the
second lever member 121b and the third lever member 121c, which are
positioned on the outer side in the paper width direction than the first
lever member 121a, are still in the drooped state. As shown in FIG. 14,
in a state the first lever member 121a is rotated, only the detecting
unit 122a detects the back end 211b of the first lever member 121a. The
determination unit determines that the paper width of the recording paper
roll 10 accommodated in the recording paper roll loading unit 110 is 203
mm from the detection result of the detecting unit 122.

[0073]Furthermore, among the recording paper roll 10 that can be
accommodated in the recording paper roll loading unit 110, the detection
of the recording paper roll 10 of A4 size (210 mm) is performed by the
second lever member 121b. When the recording paper roll loading unit 110
accommodating such recording paper roll 10 is pushed into the housing
102, the second lever member 121b contacts the flange unit 134. The
second lever member 121b rotates along the peripheral surface of the
flange unit 134 with the pushing in of the recording paper roll loading
unit 110 into the housing 102. In this case, the first lever 121a
positioned on the inner side in the paper width direction than the second
lever member 121b also rotates with the rotation of the second lever
member 121b.

[0074]In other words, when the thin-thickness portion 212m of the second
lever member 121b contacts the peripheral surface of the flange unit 134
and rotates to the upper side of the plane of drawing of FIG. 15, the
projection 212f of the second lever member 121b that engages the recess
211e of the first lever member 121a pushes up the first lever member
121a. Thus, since the first lever member 121a cooperatively rotates with
another lever member 121b, 121c positioned on the outer side in the paper
width direction than itself, the contact of the first lever member 121a
and the outer peripheral surface of the recording paper roll 10 can be
prevented.

[0075]The third lever member 121c positioned on the outer side in the
paper width direction than the second lever member 121b maintains a state
in which the contacting part is drooped even if the second lever member
121b is rotated. In other words, the engagement of the recess 212e of the
second lever member 121b and the projection 213f of the third lever
member 121c in a state in which the second lever member 121b and the
third lever member 121c are drooped is disengaged by the rotation of the
second lever member 121b. Therefore, the third lever member 121c does not
rotate by the rotation of the second lever member 121b.

[0076]In the state shown in FIG. 15, the detecting unit 122a corresponding
to the first lever member 121a and the detecting unit 122b corresponding
to the second lever member 121b detect the rotation of the lever members
121a, 121b. The determination unit determines that the paper width of the
recording paper roll 10 accommodated in the recording paper roll loading
unit 110 is 210 mm from the detection result of the detecting unit 122.

[0077]Moreover, among the recording paper roll 10 that can be accommodated
in the recording paper roll loading unit 110, the detection of the
recording paper roll 10 of LT size (216 mm) is performed by the third
lever member 121c. When the recording paper roll loading unit 110
accommodating such recording paper roll 10 is pushed into the housing
102, the third lever member 121c contacts the flange unit 134. The third
lever member 121c rotates along the peripheral surface of the flange unit
134 with the pushing in of the recording paper roll loading unit 110 into
the housing 102. In this case, the first lever member 121a and the second
lever member 121b positioned on the inner side in the paper width
direction than the third lever member 121c also rotate with the rotation
of the third lever member 121c.

[0078]In other words, when the thin-thickness portion 213m of the third
lever member 121c contacts the peripheral surface of the flange unit 134
and rotates to the upper side of the plane of drawing of FIG. 16, the
projection 213f of the third lever member 121c that engages the recess
212e of the second lever member 121b pushes up the second lever member
121b. Furthermore, the projection 212f of the second lever member 121b
that engages the recess 211e of the first lever member 121a pushes up the
first lever member 121a. Thus, since the first lever member 121a and the
second lever member 121b cooperatively rotate with the third lever member
121c positioned on the outer side in the paper width direction than
themselves, the contact of the first lever member 121a and the second
lever member 121b with the outer peripheral surface of the recording
paper roll 10 can be prevented.

[0079]In the state shown in FIG. 16, the detecting units 122a, 122b, 122c
corresponding to the three lever members 121a, 121b, 121c detect the
rotation of the three lever members 121a, 121b, 121c. The determination
unit determines that the paper width of the recording paper roll 10
accommodated in the recording paper roll loading unit 110 is 216 mm from
the detection result of the detecting unit 122.

[0080]Therefore, the paper width detection mechanism 120 according to the
present embodiment can detect the paper width of the recording paper roll
10 accommodated in the recording paper roll loading unit 110 by the
number of rotated lever members 121 detected by the detecting unit 122.
The lever member 121 rotates in conjunction with another lever member 121
positioned on the outer side in the paper width direction than itself.
Thus, the lever member 121, which is positioned on the inner side in the
paper width direction than the lever member 121 that contacts the
peripheral surface of the flange unit 134 and rotates, contacts the outer
peripheral surface of the recording paper roll 10, thereby preventing
taint damage of the recording paper, and production of small scratches
and paper powder.

[0081]The configuration and the operation of the paper width detection
mechanism 120 according to the present embodiment have been described
above. According to the paper width detection mechanism 120 according to
the present embodiment, a plurality of lever member 121 that contact the
flange unit 134 of the holder 130 for holding the recording paper roll 10
is arranged according to the paper size of the recording paper roll 10
accommodated in the recording paper roll loading unit 110. One lever
member 121 contacts the flange unit 134 and rotates with the pushing in
of the recording paper roll loading unit 110 into the housing 102. When
the recording paper roll loading unit 110 is accommodated in the housing
102, the detecting unit 122 detects the rotated lever member 121. The
paper width detection mechanism 120 can detect the paper width of the
recording paper roll 10 accommodated in the recording paper roll loading
unit 110 from the detection result of the detecting unit 122. Thus, the
paper width detection mechanism 120 can immediately detect the paper
width of the recording paper roll 10 before passing the recording paper
through the apparatus with a simple configuration of lining a plurality
of lever members 121 and detecting the rotation state of the lever
members 121 with the detecting unit 122.

[0082]The plurality of lever members 121 of the paper width detection
mechanism 120 according to the present embodiment is configured to rotate
in conjunction with another lever member 121 positioned on the outer side
in the paper width direction than itself. Thus, the lever member 121 does
not contact the surface of the recording paper roll 10 regardless of
which recording paper roll 10 of which paper width is accommodated in the
recording paper roll loading unit 110. Thus, the taint damage and
production of small scratches and paper powder, etc. at the surface of
the recording paper roll 10 can be prevented. The mistaken detection of
the paper size due to the influence of undulation of the surface of the
recording paper roll 10 can be prevented.

[0083]It should be understood by those skilled in the art that various
modifications, combinations, sub-combinations and alterations may occur
depending on design requirements and other factors insofar as they are
within the scope of the appended claims or the equivalents thereof.

[0084]For instance, in the embodiment described above, three lever members
121a, 121b, 121c are arranged in the paper width detection mechanism 120,
but the present invention is not limited to such example. For instance, a
plurality of lever members 121 may be arranged according to the size of
the recording paper roll 10 that can be accommodated in the recording
paper roll loading unit 110. The material of the lever member 121 is also
not limited to the example of the above-described embodiment.

[0085]In the above-described embodiment, the guide unit 134a formed at the
flange unit 134 is a projection-shaped guide projected out in the radial
direction, but the present invention is not limited to such example, and
may be a recess-shaped guide depressed in the radial direction. The guide
unit 134a is arranged on the outer side in the paper width direction of
the flange unit 134, but the present invention is not limited to such
example, and may be arranged on the inner side in the paper width
direction of the flange unit 134.

[0086]Furthermore, in the above-described embodiment, the sublimation
thermal printer device is used for the image forming apparatus 100, but
the present invention is not limited to such example. The device is to be
an image forming apparatus that uses the recording paper roll 10, and may
be applied to an inkjet printer or a laser printer, or may be a device
other than a printer (e.g., copying machine, facsimile).

[0087]The present application contains subject matter related to that
disclosed in Japanese Priority Patent Application JP 2008-335252 filed in
the Japan Patent Office on Dec. 26, 2008, the entire content of which is
hereby incorporated by reference.